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3 years ago

ABCD is a quadrilateral with AB equal and parallel to DC. prove that AD is equal and parallel to BC

Mathematics

1 answer:

rewona [7]3 years ago

6 0

Answer: see below proof

Step-by-step explanation:

Imagine a diagonal line AC

If AB = DC and AB // DC then angle BAC =

Angle ACD Alternate Interior angles theorem.

Then if AB = AD and angle BAC = angle ACD and AC = AC then triangle ABC is congruent to triangle CDA.

If triangle ABC is congruent to triangle CDA then AD = BC because congruent parts of congruent triangles are congruent.

If triangle ABC is congruent to triangle CDA then angle ACB = angle CAD because congruent parts of congruent triangles are congruent.

If angle ACB = angle CAD then AD // BC because of the alternate interior angles theorem.

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The cost of 5 hats and 1 scarf is $47. The cost of 2 hats and 2 scarves is $40. How much does one hat cost?

stepan [7]

Answer:

6.75

Step-by-step explanation:

h=hat, s=scarf

5h + 1s = $47 (equation 1)

2h + 2s = $40 (equation 2)

multiply equation 1 by 2 , we get: 10h + 2s = $94 (equation 3)

equation 3 minus equation 2, we get:

8h = $54 ⇒ h = $6.75 ⇔ 1 hat cost $6.75

substitute h = $6.75 into equation 2 to find s,

2($6.75) + 2s = $40

$13.5 + 2s = $40

2s = $26.5

s = $13.25 ⇔ 1 scarf cost $13.25

6 0

3 years ago

Use a proof by contradiction to show that the square root of 3 is national You may use the following fact: For any integer kirke

Ierofanga [76]

Answer:

1. Let us proof that √3 is an irrational number, using reductio ad absurdum. Assume that $\sqrt{3}=\frac{m}{n}$ where $m$ and $n$ are non negative integers, and the fraction $\frac{m}{n}$ is irreducible, i.e., the numbers $m$ and $n$ have no common factors.

Now, squaring the equality at the beginning we get that

$3=\frac{m^2}{n^2}$ (1)

which is equivalent to $3n^2=m^2$ . From this we can deduce that 3 divides the number $m^2$ , and necessarily 3 must divide $m$ . Thus, $m=3p$ , where $p$ is a non negative integer.

Substituting $m=3p$ into (1), we get

$3= \frac{9p^2}{n^2}$

which is equivalent to

$n^2=3p^2$ .

Thus, 3 divides $n^2$ and necessarily 3 must divide $n$ . Hence, $n=3q$ where $q$ is a non negative integer.

Notice that

$\frac{m}{n} = \frac{3p}{3q} = \frac{p}{q}$ .

The above equality means that the fraction $\frac{m}{n}$ is reducible, what contradicts our initial assumption. So, $\sqrt{3}$ is irrational.

2. Let us prove now that the multiplication of an integer and a rational number is a rational number. So, $r\in\mathbb{Q}$ , which is equivalent to say that $r=\frac{m}{n}$ where $m$ and $n$ are non negative integers. Also, assume that $k\in\mathbb{Z}$ . So, we want to prove that $k\cdot r\in\mathbb{Z}$ . Recall that an integer $k$ can be written as

$k=\frac{k}{1}$ .

Then,

$k\cdot r = \frac{k}{1}\frac{m}{n} = \frac{mk}{n}$ .

Notice that the product $mk$ is an integer. Thus, the fraction $\frac{mk}{n}$ is a rational number. Therefore, $k\cdot r\in\mathbb{Q}$ .

3. Let us prove by reductio ad absurdum that the sum of a rational number and an irrational number is an irrational number. So, we have $x$ is irrational and $p\in\mathbb{Q}$ .

Write $q=x+p$ and let us suppose that $q$ is a rational number. So, we get that

$x=q-p$ .

But the subtraction or addition of two rational numbers is rational too. Then, the number $x$ must be rational too, which is a clear contradiction with our hypothesis. Therefore, $x+p$ is irrational.

7 0

3 years ago

Pls in order to pass i need to finish this pls help and for 4 5 6 and only 9

Yuliya22 [10]

Answer:

7 and 8

7=a

8=b

and sssuree

9=A=100(3.14)

4) not sure butt sure like 70%

area=36(3.14)

5)9(3.14)

6)289(3.14)

hope u pass

7 0

2 years ago

What is the equation of the line that passes through the point (5, -7) and has a slope of -12

lilavasa [31]

Answer:

y = -12x + 53

Step-by-step explanation:

don't mind this hehgajhakwuzgbsldj

3 0

3 years ago

chad is making an orange smoothie. the recipe call for 3 parts of frozen yogurt to 5 parts of orange juice. how many ounces of b

Alona [7]

Answer: it will be 6 ounces of frozen yogurt and 10 ounces of orange juice.

Step-by-step explanation:

3 parts frozen yogurt

5 parts orange juice For a total of 8 parts divided by 16 ounces = 2 Multiply 3 fy x 2= 6 ounces And multiply 5 oj x 2= 10 ounces

3 0

2 years ago

ABCD is a quadrilateral with AB equal and parallel to DC. prove that AD is equal and parallel to BC​

ABCD is a quadrilateral with AB equal and parallel to DC. prove that AD is equal and parallel to BC